YELLOW FEVER. 7 i 7 



vomit, indicating-, as it does, a profound disorganization of the blood, 

 is, in most cases, a fatal sign. Alvarenga states that, in the epidemic 

 of 1857, at Lisbon, out of one hundred and seventy-eight cases of black 

 vomit, forty recovered, but this is an isolated experience, and in this 

 country, at least, such recoveries are rare. The mortality varies be- 

 tween five and seventy-five per cent, of those attacked. 



The disease develops in from one to fourteen days after exposure. 

 Those most liable to it are strangers or recent comers. Old residents 

 enjoy a certain immunity, excepting in severe epidemics, and, even if 

 they are attacked, the disease is generally mild. "Women and children, 

 old persons, and those of delicate constitutions, are visually less liable 

 to it than robust, healthy men. This year the children are said to have 

 suffered most. The negro natives are generally exempt, though it has 

 been noticed that negroes who have left the South for the North, and 

 have returned during an epidemic, do not possess this immunity. In 

 the present epidemic, even the negroes seem to succumb in great num- 

 bers. It is a singular fact that persons exposed to offensive effluvia 

 when working at their trade, as tanners, butchers, soap-boilers, and 

 scavengers, are almost exempt from the disease, while those whose 

 trade exposes them to great variations of temperature, as bakers and 

 cooks, are extremely prone to it. Like small-pox, it may occur more 

 than once in the same person, but, as a rule, those who have had it 

 once are never attacked again. 



All methods of treatment agree in the principal points. The bowels 

 must be cleared at the start, and the patient kept perfectly quiet. The 

 temperature is kept down by applications of cold water, and ice is 

 applied to the head if symptoms of congestion of the brain appear. 

 The excessive thirst is relieved by swallowing lumps of ice, and the 

 nausea controlled to some extent by iced lemonade or champagne. In 

 the West Indies, lemon-juice plays an important part in the treatment, 

 and the old negro nurses rub it over the surface of the bod} 7 . When 

 the appetite revives, great caution has to be exercised, as a premature 

 return to solid food may result fatally. 



The first fully recorded outbreak of the disease was in the West 

 Indies in 1647, and since then it has recurred at irregular intervals, and 

 has gradually extended its range. Epidemics have occurred as far 

 north as Quebec and as far south as Montevideo, as far west as 

 Mexico and as far east as Algiers. It is endemic in the West Indies, 

 Venezuela, New Granada, and Mexico, on the easterly coast of the 

 United States as far north as Charleston, South Carolina, and on the 

 northerly coast of Africa. To become epidemic, it requires a mean 

 temperature of at least 72, and Griesinger holds that the temperature 

 must be as high as 80 for a considerable time before it can acquire a 

 foothold, though West Indian physicians have seen the temperature 

 fall suddenly just before an outbreak. If the temperature falls during 

 an epidemic its severity abates, and at 32 it disappears entirely. It 



